Process for preparing 1-lithium-1-alkynes



United States Patent 3,418,385 PROCESS FOR PREPARING l-LlTHIUM-l-ALKYNES David L. Skinner, Arlington Heights, 11]., and Donald J.Peterson, Springfield Township, Ohio, assignors to The Procter & GambleCompany, Cincinnati, Ohio, a corporation of Ohio No Drawing. Filed Sept.27, 1966, Ser. No. 582,249 4 Claims. (Cl. 260-665) This inventionrelates to a novel process for preparing certain organolithiumcompounds. More particularly, this invention relates to a novel processfor preparing 1- lithium-l-alkynes.

Reaction processes for obtaining l-lithium-l-alkynes are known, butgenerally these reaction processes are complicated. More importantly,these known reaction processes generally require a l-alkyne as astarting material, and such a alkynes are not always readily available.Illustrative of these problems is the process of preparing lithiumacetylides (l-lithium-l-alkynes) described in R. A. Raphael, AcetylenicCompounds in Organic Synthesis (Academic Press, New York, N.Y., 1955).In the process described there, a l-alkyne is converted into a mercuridecompound according to the following reaction and the organic mercuridewhich is obtained is then reacted with lithium metal in hot dioxansolution to obtain the desired l-lithium-l-alkyne RC2 CLi Other equallycomplex processes for preparing l-lithiuml-alkynes are known.

This invention has as its object the provision of a much improved novelprocess for producing certain l-lithiuml-alkynes.

It is another object of this invention to provide 1- lithium-l-alkynesby a process that does not require 1- alkynes as starting raw materials,but instead employs more readily available alpha olefins, i.e.,l-alkenes.

The l-lithium-l-alkynes which can be prepared by the process of thisinvention contain from about four to about twelve carbon atoms, and arerepresented by the formula RC E CLi wherein R is an alkyl groupcontaining from about two to about ten carbon atoms.

It has been quite unexpectedly found that these 1- lithium-l-alkynes canbe obtained by reacting finely divided lithium metal with a l-alkenehaving a carbon chain length corresponding to the carbon chain length ofthe 1- lithium-l-alkyne desired to be obtained. A preferred process foreffecting this recation comprises heating a lalkene containing adispersion of finely divided lithium at a temperature of from about C.to 175 C. for a period of from about .5 hour to about 40 hours. Mostpreferably the mixture of the l-alkene and the finely divided lithiumparticles is heated to a reflux temperature or up to a temperature ofnot more than 100 C. for the higher boiling l-alkenes. The reactionproceeds at higher temperatures, but undesirable side reactions occur.The reaction also proceeds at temperatures lower than those specified,but the yields are not as favorable as those obtained when highertemperatures are used.

The particles of lithium used in the reaction are finely divided so thatthe particles are 100 microns or less in size, preferably less than 100microns. There is no limit on how small the lithium particles useful inthe reaction can be, but particles as small as 1 micron are useful. Mostpreferably the lithium particles are from about 10 microns to aboutmicrons in size.

The proportions in which the reactants, lithium particles and l-alkene,are used is not critical. However, it is preferred to use an amount ofthe l-alkene being reacted in excess of the amount that will react withlithium. A desirable, but not unduly large, excess of l alkene isprovided by using from about 1 mole to about 2 moles of the l-alkenebeing reacted per mole of lithium.

It is preferred, but not necessary, to agitate the reaction mixture, asfor example by stirring, in order to mix the reactants well.

It is also preferred that the reaction be conducted under the atmosphereof a gas that will not, under conditions of the reaction, react with thelithium particles or the organolithium products of the reaction. Thepreferred gases for this purpose are the noble gases, preferably heliumand neon, and most preferably argon.

The l-alkenes which can be used in this invention range in carboncontent from 4 to 12 carbons, including l-butene, l-pentene, l-hexene,l-heptene, l-octene, l-nonene, l-decene, l-undecene, and 1-dodecene.Certain of these l-alkenes react very readily with finely dividedlithium. In particular, l-pentene, l-hexene, and 1-heptene are readilyconverted in good yield to the corresponding l-lithium-lpentyne,l-lithium-l-hexyne, and l-lithium-l-heptyne by refluxing for from .5 to8 hours the l-alkene containing a quantity of finely divided lithiumdispersed therein. The reaction between l-butene and lithium particlesalso proceeds readily, but the procedure for this reaction differsslightly from the above procedure because l-butene has a rather lowboiling point. Because of the low boiling point of l-butene it ispreferred to conduct the reaction between l-butene and lithium in anautoclave at from about 50 C. to about C. The autoclave is preferably arocking autoclave, since with such an autoclave the lithiumbutenemixture can be agitated.

It has also been discovered according to the present invention, thathigher olefins containing from about 8 to about 12 carbon atoms can bemade to react with lithium by employing a compound which promotes thereaction. Since pure olefins within this range do not readily react withlithium, it is necessary to promote the reaction' It has beensurprisingly found that l-alkenes containing from about eight to abouttwelve carbon atoms react with finely divided lithium in the process ofthis invention to give the corresponding l-lithium-lalkyne if thereaction is carried out in the presence of certain compounds having anactive hydrogen that promotes the reaction. Such chemical compounds aredesignated herein as active hydrogen compounds. A suitable temperaturerange for the reaction between carbon-8 to carbon-12 olefins and lithiumis from about 100 C. to about C.

Active hydrogen compounds that are useful as chemical promoters in theprocess of this invention are (1) ammonia; (2) primary amines,preferably having an alkyl group containing from about one to abouttwelve carbon atoms, specific examples being methyl amine, propyl amine,and dodecyl amine; (3) secondary amines, preferably having alkyl groupswith from about one to about twelve carbon atoms, the most preferredspecific examples being dimethyl amine and methyl dodecyl amine; (4)water; (5) primary alcohols, preferably having an alkyl group containingfrom about one to about twelve carbon atoms, specific examples beingpropanol and dodecanol, the most preferred specific examples beingmethanol and ethanol; (6) secondary alcohols, preferably having alkylgroups containing from about one to about twelve carbon atoms, specificexamples being 2-hexanol, 4-decanol, and 7-hexadecanol; (7) tertiaryalcohols, preferably having alkyl groups containing from about one toabout twelve carbon atoms, specific examples being 2-methyl-2-propanol,

3 3-methyl-3-decanol and 2-methyl-2-hexanol; (8) ammonium salts,preferably ammonium acetate, ammonium chloride, and ammonium bromide;(9) l-alkynes, preferably having from about four to about seven carbonatoms, the most preferred specific examples being l-butyne, l-pentyne,and l-hexyne; (l) anhydrous hydrogen chloride gas, and the like. JustWhy these compounds promote the reaction is unknown, but compounds withactive hydrogen atoms appear to be the compounds that are efficacious aspromoters. Many compounds will promote the reaction, but those listedabove can be especially useful.

Generally only a small amount, from about one mole percent to aboutfifteen mole percent, preferably from about five mole percent to aboutten mole percent, based on the amount of lithium present, of thechemical promoter is employed. The promoter can all be added to thel-alkene before the lithium dispersion is added to the reaction mixture;however, the promoter is preferably utilized by adding it slowly to theheated reaction mixture over a period of from about 0.5 hour to 10hours. Gaseous promoters, such as hydrogen chloride, are introducedbelow the surface of the reaction mixture, while liquid and solidpromoters, such as water and ammonium acetate, are dropped on thesurface of the reaction mixture. It is possible, of course, to add thepromoter in many other ways, since the method of adding the promoter isnot critical.

By using a chemical promoter, it is possible to utilize the process ofthis invention as herebefore described to convert l-octene, l-nonene,l-decene, l-undecene, and l-dodecene to the correspondingl-lithium-l-octyne, l-lithium-l-nonyne, l-lithium-l-decyne,l-lithium-l-undecyne, and l-lithium l-dodecyne.

The novel reaction process of this invention can be represented asfollows:

wherein R is an alkyl group containing from about two to about tencarbon atoms. The reaction appears to require four lithium atoms perl-alkene molecule converted. A very valuable by-product of the reactionis lithium hydride, a product which is known to have many valuable uses.The novel reaction process disclosed herein is an especially valuableprocess for obtaining lithium hydride because the process is simple andthe reaction conditions are mild. Along with the l-lithium-l-alkynesmall amounts of the corresponding l-lithium-l-alkene (generally lessthan 5%) are also produced. While the exact mechanism of the reactionprocess of this invention is unknown, the following sequence ofequations is presented as a possible course of the reaction process:

LiH 2Li 11 0:0113 ROE-CH Li i 2Li RCH=CHLi RC CLi 2LiH In this reactionsequence, R is an alkyl group containing from about two to about tencarbon atoms.

The process described hereinbefore is novel. While the literaturecontains many reports describing reactions of alkali metals with olefinscontaining double bonds in conjugation with a center of unsaturation(see G. E. Coates, Organo-Metallic Compounds, 2nd ed., John Wiley andSons, Inc., New York, 1960, pp. 2742), no reaction of the sort disclosedherein has heretofore been reported.

The process of this invention is useful in that it producesl-lithium-l-alkynes containing from about four to about twelve carbonatoms.

The l-lithium-l-alkynes of this invention are useful compounds for theyare valuable intermediates to many useful acetylenic compounds. Thefollowing reactions involving l-lithium-l-alkynes are given merely toillustrate the versatile nature of these compounds as intermediates, andshould in no way be considered as limiting since many other uses areknown, and will be obvious to those skilled in the art.

The l-lithium-l-alkynes of this invention are convenient intermediatesto the corresponding l-alkynes. These l-alkynes can be obtained byhydrolyzing the l-lithiuml-alkynes of this invention according to thegeneral equation Alkynes with internal unsaturation can also be preparedby reacting the l-lithium-l-alkynes of this invention with theappropriate alkyl halide according to the equation wherein R is an alkylgroup, and X is a halogen selected from the group consisting ofchlorine, bromine, and iodine.

The l-lithium-l-alkynes of this invention are useful in the preparationof ALB-alkynoic acids having from about five to about thirteen carbonatoms. These acetylenic carboxylic acids are prepared from thel-lithium-l-alkynes of this invention by reacting the l-lithium-l-alkynewith carbon dioxide, and then hydrolyzing the resultant prodnet. Thisreaction process is illustrated by the following equations:

I! ll RC C-O-OLi H2O RCEC-C-OH LiOH The alkynoic acids which areprepared by utilizing the l-lithium-lalkynes of this invention areuseful bactericides and fungicides. These alkynoic acids themselves arealso useful as intermediates to other chemical compounds of commercialvalue. It is well-known for example that the simple esters of A2,3-octynoic and A2,.3 -nonynoic acids have an odor resembling that ofviolets and have found commercial application as perfumes. See, Johnson,Acetylenic Compounds, vol. II (Longmans, Green & Co., 1950), p. 97.

The l-lithium-l-alkynes of this invention are also useful in thepreparation of certain organosilanes, especially acetylenicorganosilanes such as those disclosed in U.S. Patent 2,671,795. Theseorganosilanes are prepared from the l-lithium-l-alkynes of thisinvention by reacting the l-lithium-l-alkyne with an organohalosilaneaccording to the equation wherein R is a monovalent hydrocarbon radical,including saturated aliphatic radicals (specific examples being methyland dodecyl), unsaturated aliphatic radicals (specific examples beingvinyl and allyl), aryl radicals (specific examples being phenyl andnaphthyl), and alkylaryl radicals (specific examples being benzyl andphenylbutyl), and wherein X is a halogen selected from the groupconsisting of chlorine, bromine, and fluorine. Acetylenic siliconproducts such as those obtained from the above-mentioned reaction aredisclosed in the above-mentioned patent to be useful starting materialsfor various polymeric compositions. It is further disclosed that thesematerials may be polymerized with various vinyl polymerization typecatalysts,.e.g., benzoyl peroxide, to make polymeric materials havingutility as insulating or dielectric media.

The organolithium compounds of this invention are much like Grignardreagents in that they are highly reactive, and are useful primarily asintermediates to other compounds. The compounds are distinct chemicalentities, but because they are so reactive it is not generally useful orpractical to isolate these compounds.

The following examples describe with particularity the performance ofthe invention described hereinbefore. It will be obvious to thoseskilled in the art that the invention can be performed in numerous otherways. These examples are, therefore, given by way of illustration andnot by way of limitation.

EXAMPLES 1-7 The lithium used in the following examples was purchasedfrom the Foote Mineral Company in the form of particles 100 microns orsmaller in size dispersed in paraffin oil. Olefins were used as receivedfrom the supplier and were not purified before use. The lithium metaldispersion was washed twice with hexane and once with the olefin withwhich it was to be reacted. The lithium was then washed into a flaskwith the desired amount of l-alkene. The flask was equipped with amagnetic stirrer, thermometer, and condenser. The contents weremaintained under an atmosphere of argon, and the temperature wasmaintained as indicated. The reaction mixture was rapidly stirred bymeans of the magnetic stirrer. After the indicated length of time hadpassed, the reaction mixture was allowed to cool. The highly reactivel-lithium-lalkyne formed was then converted into a useful acetyleniccarboxylic acid by carbonation and hydrolysis by the following process.The slurry obtained from the reaction of lithium and l-alkene was pouredover Dry Ice. The product obtained was hydrolyzed by very careful (slow)addition to ice. This fluid mixture separated into two distinct phases.The organic phase was separated from the aqueous phase and dried overMgSO after water washing. The water layers were combined and acidifiedwith concentrated HCl, extracted with ethyl ether, and the aqueous phasediscarded. The ether extract was dried over MgSO and the ether removedunder reduced pressure. Examples l-7 give the conditions and the yieldsobtained in a number of runs in which l-alkenes were reacted accordingto the above procedure.

one hour. The liquid portion of the reaction mixture was then drainedinto chilled aqueous ammonium chloride. The organic phase was extractedwith ethyl ether, dried over sodium sulfate, concentrated, and distilledunder vacuum. A reaction product containing 6.01 g. of 1-hexynyltrimethylsilane was obtained.

EXAMPLE 9 Employing the apparatus and procedure employed in Example 8,1.4 g. (0.2 g. atom) of lithium particles 100 microns or less in sizedispersed in paraffin oil were washed free of protective paraflin oiland reacted with 60 ml. (38.4 g., 0.55 mole) of l-pentene by heating themixture of lithium particles and l-pentene to about C. for 1.5 hours toform l-lithium-l-pentyne. The l-lithium- 1-pentyne formed was thentreated with 5 ml. of tetrahydrofuran and 8.5 g. (0.08 mole) ofchlorotrimethyl silane according to the procedure employed in Example 8to give 266 g. of the useful organosilane derivative,l-pentynyltrimethylsilane.

EXAMPLE 1O Employing the apparatus and procedure employed in Example 8,1.75 g. (0.25 g. atom) of lithium particles 100 microns or less in sizedispersed in paraffin oil were washed free of the protective paraffinoil and reacted with 53 ml. (37 g., 0.38 mole) of l-heptene by heatingthe mixture of lithium particles and l-heptene to about 95 C. for 1.25hours to form l-lithium-l-heptyne. The l-lithiuml-heptyne formed wasthen treated with 10 ml. of tetrahydrofuran and 8.5 g. (0.08 mole) ofchlorotrimethyl- EXAMPLE 8 The lithium used in the reaction waspurchased from the Foote Mineral Company in the form of lithiumparticles 100 microns or less in size dispersed in paraffin oil. Theapparatus for conducting the reaction consisted of a 3-necked roundbottom Grignard flask that had a sintered glass filter incorporated intothe taper of the flask immediately above the stopcock. This apparatusallowed the removal, under argon, of the protective paraffin oil fromthe air-sensitive lithium particles by successive was ings with hexaneand the l-alkene employed in the reaction. This Grignard flask wasfitted with a condenser, a stirrer, and a thermometer. Heating waseffected by means of a lamp. Using the above-mentioned apparatus, theprocedure employed was as follows. To the modified Grignard flask anamount of lithium dispersed in paraffin was added, so that when theparaflin oil was washed away 1.75 g. (0.25 g. atom) of lithium would beleft in the flask. When the parafiin-lithium dispersion was added to theflask, the flask was flushed with argon, and the parafiin-lithiumdispersion was then washed successively with two ml. portions of hexane,and 20 ml. of the l-alkene employed (in this case l-hexene). Afterwashing, ml. (47 g., 0.56 mole) of l-hexene was added and this mixturewas heated to about 63 C. for 1.5 hours. The reaction mixture wasstirred vigorously during this time. The mixture was allowed to cool.The highly reactive l-lithium-l-hexyne formed was then converted into auseful organosilane derivative according to the following procedure.There was added to the cooled reaction mixture 15 ml. of tetrahydrofuranto facilitate the following reaction with chlorotrimethylsilane. Themixture was stirred briefly, and 8.5 g. (0.08 mole) ofchlorotrimethylsilane was then added dropwise, resulting in anexothermic reaction. The mixture was stirred for about silane accordingto the procedure employed in Example 8 to give 4.1 g. of the usefulorganosilane derivative 1- heptynyltrimethylsilane.

EXAMPLE 11 The apparatus employed in Example 8 was fitted with means foradding a liquid dropwise to the reaction mixture. Employing thismodified apparatus and the procedure employed in Example 8, 1.75 g.(0.25 g. atom) of lithium particles microns or less in size dispersed inparaffin oil were washed free of the protective parafiin oil and reactedwith 70 ml. (50 g., 0.45 mole) of l-octene by heating the mixture oflithium particles and l-octene to about 100 C. Over a period of 1 hour0.4 g. (0.022 mole) of water (a chemical promoter) was added dropwise tothe reaction mixture. The reaction mixture was stirred while temperaturewas maintained at 100 C., for an additional 1.5 hours and then allowedto cool to room temperature. The l-lithium-l-octyne formed was thentreated with 15 ml. of tetrahydrofuran and 8.5 g. (0.08 mole) ofchlorotrimethylsilane according to the procedure employed in Example 8to give 5.2 g. of the useful organosilane derivative1-octynyltrimethylsilane.

EXAMPLE 12 When in Example 11, 0.022 mole of the following chemicalpromoters are substituted for water, substantially the same results canbe obtained in that l-lithium-loctyne is formed and the usefulorganosilane l-octynyltrimethylsilane is obtained: ammonia, methylamine,dimethylamine, methyldodecylamine, methanol, ethanol, 2- hexanol,3-methyl-3-decanol, ammonium acetate, l-hexyne, anhydrous hydrogenchloride gas (the gas being added at a constant rate below the surfaceof the olefin by a power-driven syringe).

7 EXAMPLE 13 Employing the apparatus and procedure employed in Example11, 1.75 g. (0.25 g. atom) of lithium particles 100 microns or less insize dispersed in paraifin oil were washed free of the protectiveparafiin oil and reacted with 50 ml. (37 g., 0.26 mole) of l-decene byheating the mixture of lithium particles and l-decene to about 100 C.Over a period of 1 hour, 0.35 g. (0.02 mole) of water (a chemicalpromoter) was added dropwise to the reaction mixture. After 35 hourstotal reaction time the reaction mixture was cooled to room temperature.The l-lithiuml-decyne formed was treated with ml. of tetrahydrofuran and8.5 g. (.08 mole) of chlorotrimethylsilane according to the procedureemployed in Example 8 to give 1.9 g. of l-decynyltrimethylsilane.

EXAMPLE 14 When in Example 13, 0.022 mole of the following chemicalpromoters are substituted for water, substantially the same results canbe obtained in that l-lithium-ldecyne is formed and the usefulorganosilane l-decynyltrimethylsilane is obtained: ammonia,methylarnine, dimethylamine, methyldodecylamine, methanol, ethanol,2-hexanol, 3-methyl-3-decanol, ammonium acetate l-hexyne, anhydroushydrogen chloride gas (the gas being added at a constant rate below thesurface of the olefin by a power-driven syringe).

EXAMPLE 15 When in Example 13, 0.26 mole of l-dodecene is substitutedfor l-decene, l-lithiumJ-dodecyne is obtained which is readily convertedto the useful organosilane derivative, 1-dodecyltrimethylsilane.

EXAMPLE 16 EXAMPLE 17 A mixture of 3.5 g. (0.5 g. atom) of lithiumparticles 100 microns or less in size (which had been washed free ofprotective paraflin oil) and an excess of l-butene was heated at 50 C.for 16 hours in a rocking autoclave. After exhausting the excessl-butene, the bomb liner was removed, and cooled to room temperature.The contents, which contained the l-lithium-l-butyne formed, weretreated with 50 ml. tetrahydrofuran and 17 g. (0.16 mole) ofchlorotrimethylsilane. About 0.11 g. of 1- butynyltrimethylsilane wasobtained.

In all chemical formulae appearing herein R is designated to be an alkylgroup containing from about two to about ten carbon atoms, unlessotherwise specified.

What is claimed is:

1. A process for preparing lalithium-l-alkynes of the formula RCECLiwherein R is an alkyl group containing from about 2 to about 10 carbonatoms comprising reacting (1) a l-alkene compound having from about 4 toabout 12 carbon atoms, and (2) finely divided lithium at a temperatureof from about 20 C. to about 175 C.

2. The process of claim 1 wherein the particles of lithium are micronsor less in size.

3. The process of claim 1 wherein the l-alkene compound has from about 4to about 8 carbon atoms.

4. A process for preparing l-lithium-l-alkynes of the formula RCECLiwherein R is an alkyl group containing from about 6 to about 10 carbonatoms comprising reacting (1) a 1- alkene compound having from about 8to about 12 carbon atoms, and (2) finely divided lithium having aparticle size of 100 microns or smaller in presence of an activehydrogen compound at a temperature of from about 100 C. to about C.

References Cited UNITED STATES PATENTS 9/1962 Viehe 260'665 OTHERREFERENCES TOBIAS E. LEVOW, Primary Examiner.

A. P. DEMERS, Assistant Examiner.

US. Cl. X-R.

1. A PROCESS FOR PREPARING 1-LITHIUM-1-ALKYNES OF THE FORMULA